Steel I-beams are frequently used to build frameworks for large buildings and construction projects. The beams are connected together with bolts that must be positioned precisely given the large scale of the building. When the bolts are positioned even ⅛ of an inch off center, the stability of the project is endangered as the error is compounded over tens or hundreds of feet.
The measurement process is complicated by the fact that measurements are defined from the outside of the beam flange, while the hole itself is drilled in the beam web. Thus, it is impossible to use a standard tape measure, for example, to measure the required distance directly. Instead, a square is generally used in combination with a tape measure, to make the appropriate measurement.
More particularly describing the prior art as shown in FIGS. 1–4, an I-beam 10 comprises a web 11 and two side flanges 12. Typically, the intersection of web 11 and flanges 12 is rounded rather than square, defining radius 13 at the web/flange intersection.
To measure the locations of holes to be drilled in the beam, a tape measure 14 is first used to measure predetermined distances from one end of the beam. Marks 15 are used to indicate those distances. A square 17 is then used to mark lines 16 perpendicular to the flanges at those measured distances, generally by positioning the square an indicated in FIG. 3. Square 17 is then turned on its end and is used in conjunction with tape 14 to mark distances from the outside of the flange, as shown in FIG. 4. Square 17 and tape 14 generally cannot be used to measure that distance directly, due in large part to the curvature of the intersection between the web and the flange.
The precision of the foregoing method of measurement depends, in part, on whether the flanges are truly at right angles to the web. If one flange is bent in or out a little, the distance measured from the top of the flange will not be the same as the distance along the web. This leads to errors in marking holes, since the method uses distances from the top of the flange as a guide. In addition, the speed of the foregoing method is unsatisfactory since multiple tools and measurements are required for each point.
A need therefore exists for a method of measuring and marking lines and points on I-beams that doesn't require a combination of tools, and that is more exact than the method of the prior art. The present invention addresses that need.